The present invention relates to a cutting insert, a cutting tool for chip removing machining, a shim as well as a method for mounting a cutting insert according to the preambles of the independent claims.
In tools for metal machining round cutting inserts of hard and wear resistant material such as cemented carbide are often used. A problem, which is created at use of round cutting insert, is that the cutting insert tends to be twisted arbitrary in the holder both by the operator and by the cutting forces. Through a number of documents, for example U.S. Pat. Nos. 6,146,060, 5,478,175, 3,383,748 and 5,346,336 different solutions are proposed in order to lock the round cutting insert in the holder. Round cutting inserts have a problematic chip-breaking pattern.
Round cutting inserts have, for example, a difficulty with breaking chips at small cutting depths and at small feeds. There are, however, round cutting inserts with chip breaker that to some extent solve the later problem such as in U.S. Pat. Nos. 5,478,175 and 3,383,748. In U.S. Pat. No. 5,346,336 a circular cutting insert is shown provided with five plane facets distributed at even partition on the clearance surface. The facets are provided to constitute defined positions in connection with indexing of the cutting insert. Each facet forms an acute angle with the center axis of the cutting insert. A locking screw locks the cutting insert to the pocket of the holder insert. A problem with the latter circular cutting insert is that it has difficulties to break chips at small cutting depths and small feeds.
Other documents showing circular cutting inserts are JP Patent Document No. 08-174311 and U.S. Pat. No. 6,164,878.
It is desirable to provide a cutting insert, which avoids the above-captioned drawbacks.
It is also desirable to provide a cutting insert, which can break chips at small cutting depths and small feeds.
It is also desirable to provide a cutting insert, which comprises a built-in positioning of the chip breaker portion.
It is also desirable to provide a tool and a cutting insert that comprise an adjustable chip breaker portion.
It is also desirable to provide a tool, a cutting insert, a shim and a method, wherein the cutting insert can be indexed exactly in a simple manner.
According to an aspect of the present invention, a cutting insert for chip removing machining comprises a substantially circular cutting edge formed at a transition between an upper side and an edge surface of the cutting insert, the upper side comprising a chip surface including at least one chip breaker portion and the edge surface comprising a clearance surface, the edge surface connecting to a lower side of the cutting insert, the lower side comprising at least one of a projection and a recess for indexing of the cutting insert. The chip breaker portion is provided at a varying distance from the associated cutting edge, the at least one of the projection and the recess is provided at a position relative to a reference line or axis of the tool in order to orient the chip breaker portion in the chip surface to a desired position, and a quantity of chip breaker portions is a multiple of a quantity of the at least one of the projection and the recess.
In accordance with another aspect of the present invention, a circular shim for a cutting tool as described above is provided. The shim is adapted to be placed in the at least one insert pocket in order to support a circular cutting insert in the cutting tool. The shim comprises opposite first and second surfaces and a central hole. The first surface of the shim comprises an abutment surface for abutting against the at least one insert pocket, and the second surface of the shim comprises an abutment surface for abutting against the circular cutting insert and at least one of a projection and a recess for indexing of the cutting insert.
In accordance with another aspect of the present invention, a method for mounting a cutting insert in a holder for chip removing machining is provided. The cutting insert has a substantially circular basic shape and comprises at least one cutting edge formed at a transition between an upper side and an edge surface of the cutting insert. The upper side comprises a chip surface comprising at least one chip breaker portion and the edge surface comprising a clearance surface. The cutting tool comprises a clamp for holding the cutting insert and the holder together. The cutting insert has at least one of a projection and a recess on its lower side. According to the method, a holder including at least one insert pocket with a base surface is provided. A circular shim is provided in the insert pocket, the shim comprising opposite first and second surfaces and a central hole, the first surface comprising an abutment surface for abutting against the base surface, the second surface comprising at least one of a projection and a recess for mating with the at least one of the projection and the recess on the lower side of the cutting insert. The cutting insert is provided with a quantity of chip breaker portions that is a multiple of a quantity of the at least one of the projection and the recess on the lower side of the cutting insert. The shim is screwed, with a screw, in position relative to the base surface such that the shim can be rotated. The cutting insert is positioned on the shim in such a manner that at least one of the at least one of the projection and the recess on the lower side of the cutting insert fits to a counterpart one of the at least one of the projection and the recess on the second surface of the shim. The cutting insert and the shim are rotated together until a desired position for the chip breaker portion relative to the holder has been obtained. The cutting insert is removed and the screw is tightened such that the shim is fixed in a desired position. The cutting insert is mounted in the position and the cutting insert is fixed in the pocket by a clamping arrangement.